A new study published Monday in the journal Nature Climate Change links rising temperatures to increased rates of suicide. The research is among the first to look into the effects climate change could have on a person’s mental health.
The research took monthly suicide statistics from the U.S. and Mexico over multiple decades and compared the data with temperature and precipitation information. Other factors, such as seasonal variation, poverty levels, and other suicides in the headlines, were also taken into account, according to a Guardian report.
“We take a specific location and we take a specific month, and we compare cooler versions of that month to hotter versions of that month, and we ask, ‘Are suicide rates different during those two months?’ We indeed find that they are,” Marshall Burke, an assistant professor at Stanford University and lead author of the study, told KTLA5 News.
The data analysis found that suicides rates rise 0.7% in U.S. counties and 2.1% in Mexican municipalities when there’s a 1 degree Celsius increase in monthly average temperature. The rates are comparable to those created by an economic recession, the scientists report.
“We find a very consistent relationship between temperature increases and increases in suicide risk,” Burke said, adding that suicide is a “very complex phenomenon,” and there are many other factors besides climate that can play into suicide risk.
The World Health Organization reports nearly 800,000 people die due to suicide each year; it’s the second leading cause of death among 15- to 29-year-olds.
Burke’s research also compared temperature data to the rates of depression-related words (“lonely,” “suicidal,” “trapped,” etc.) in more than 600 million Twitter posts. They found that the 1 degree Celsius increase in monthly average temperature correlated to an increase in Twitter posts with depressive language.
More research is needed to examine this link, but other studies provide some background to the link between human behavior and increased temperatures.
“Studies suggest that some components of brain chemistry, in particular certain neurotransmitters, are important in both mental health and in how the body regulates its internal temperature,” Burke told KTLA5 News. “That to us suggests at least there’s a plausible biological linkage between temperature, thermal regulation and how the brain regulates its own emotion.”
If current climate change trends continue, the scientists projected that increased heat could cause between 9,000 and 40,000 additional suicides in the U.S. and Mexico by 2050.